Fraction of secondary decays

jackfrost373 / LHCb_Xic_production

Honours programme analysis at MSP for MSP honours students, measuring the production ratio of Xi_c over L_c in the LHCb experiment.

2 stars 4 forks source link

Fraction of secondary decays #17

Open jackfrost373 opened 5 years ago

jackfrost373 commented 5 years ago

We should finalize how we remove secondary decays (TIP / IPchi2), and assess how much secondary decays will be left in our final selection. One way to do that, is to make fit templates (using e.g. bifurcated gaussians) of the IPchi2 / TIP distribution from MC, and fix those shapes and fit them in data. The amount of secondaries will be a systematic error to our result, so should be reduced as much as possible.

jackfrost373 commented 5 years ago

Aleksei wants to take this on.

[x] Jacco to provide tuple of secondary B -> D decays

jackfrost373 commented 5 years ago

[x] Needs data for run2, one type, without the IPchi2 < 9 cut in stripping line
[ ] Do study of optimal cut point on IPchi2 - secondary fraction (pollution) as systematic, vs the relative stat. error on the signal yields.

jackfrost373 commented 4 years ago

Aleksei made a generic tool for these studies, available here: https://bitbucket.org/alleksha/yc-bar/src/master/

Based on his presentation from 25 Oct, which uses the above produced samples, the prompt fraction is about 80% for Lc, and around 95% for Xic, and varies only a little bit depending on y and pT. Fits to the IPchi2 show that a cut on the IPchi2 < 1 will removes the largest peak of secondary decays (>50%), while having only a small impact on the signal yield. This cut could be optimized though.

jackfrost373 commented 4 years ago

[ ] MC studies of secondaries?

cpawley commented 4 years ago

Still ongoing. Should we check in with Aleksai again on this?